Development Of Three-Dimensional Finite Element Models Of The Human Head-neck And Analysis Of Direct Head Impact Injury

Traumatic head injury is one of the major causes of human death and disability. The mechanism of impact human brain injury is not completely illuminated. Impact biomechanics has been the subject of much study. The researching methods include animal experiment, cadaver experiment, biomaterial mechanic study and mathematical modeling. Finite element analysis is one of the best ways of investigating the impact brain injury mechanisms. We developed three-dimensional head-neck finite element models using digital CT and MRI data of a normal Chinese male head. The model was validated on the basis of the transient response. The calculated intracranial pressures were comparable to those measured by Nahum et al. The parametric study has also been done. The development of frontal and occipital head impact injury was simulated with the finite element model. With both the calculated results and imaging findings of clinical cases, the mechanism of impact brain injury was discussed. The main studies were as follows: Development of a three-dimensional finite model of the Chinese head-neckBased on a series of two-dimensional computer tomography images and magnetic resonance images of a normal adult Chinese male head-neck, a three-dimensional finite element model was developed. A three-dimensional reconstruction method of the human head is proposed based on medical image contour point extraction. A foundation is provided for the 3-D finite element modeling and the physical model manufacturing of the human head. The model includes: facial cranium, scalp, skull, skull base, dura(cerebral falx, tentorium cerebelli), venous sinus(superior sagittal sinus, transversal sinus, sig-moid sinus), brain(gray matter , white matter),corpus callosum, basal nucleus, dien-cephalon, brain stem, cerebellum, ventricle system, cervical vertebra, et al. A parametric study and validation of the three-dimensional human head finiteelement modelBased on the experimental data on the constitutive properties of brain, skull and dura, they were assumed to be homogeneous and isotropic with linear elastic behavior. The used data of Young's moduli, Poisson's ratio and mass density was presented in previous literatures. A series of structural damping factors for skull and brain were used to simulate a frontal head impact. The calculated results of Von Mises stress of skull and brain were observed. We conclude that the skull structural damping factor influence the skull stress greatly. It is proper to define skull structural damping factor between 0.001 and 0.004. The brain stress curves changed with skull stress curves. After the atlantooc-cipital joint simulated, using 3D spring element, the skull stress curve became more smoothly. The 3D finite element model was validated by comparing the numerical and experimental results for the transient response to an impact on the frontal bone. The ca-daver experimental was performed by Nahum et al. in 1977, in which the intracranial pressures of different parts of the head were measured by piezo resistive pressure transducers. When the major stress data of dura node were used to calculate intracranial pressures, the computed pressure time histories at 3 locations compared favorably with cadaver experimental data. The model provided a reasonable level of confidence in the model accuracy. Modeling skull-brain relative displacementRelative displacement between skull and brain may complain many types of brain injury, such as cerebral contusions, which was accepted by most clinicians. In the view of anatomy and histology, the skull connects dura closely, and the pia mater-arachnoid also connect gray matter closely. In our opinion, the skull-brain relative displacement occurs in the subdural space, not the layer of cerebrospinal fluid. A type of spring element was used to simulate the subdural space. With proper parameters, the relative displacement between skull and brain was observed in simulating frontal head impact. The areas of changes of brain surface stress moved to the brain base, which agreed more with clinical...